1. Technical Field
The present invention relates to a horizontal deflection circuit for use in a video display monitor or television set having a CRT (cathode ray tube), and more particularly to high-frequency horizontal deflection output circuit for obtaining high picture quality.
2. Related Art
In either a display monitor or a television set having a CRT, externally supplied video signals are amplified and supplied to electron guns within the CRT to emit electron beams. At the same time, synchronizing signals, (that is, horizontal and vertical synchronizing signals) are applied to horizontal and vertical deflection circuits, respectively. Then, the deflection circuits supply horizontal and vertical deflection signals to horizontal and vertical deflection yokes, respectively, around the neck of the CRT. Accordingly, the electron beams are deflected under the control of the deflection circuits in the horizontal and vertical directions relative to the beam emitting directions.
Generally, the horizontal deflection circuit may have a phase-locked loop (PLL), an oscillator, a horizontal drive circuit for generating a horizontal driving pulse signal, and a horizontal deflection output circuit for supplying a saw-tooth wave current to the horizontal deflection yoke.
As stated in more detail below, conventional horizontal deflection output circuits employ, as one component thereof, a bipolar transistor which becomes saturated when it is operating as a closed switch; that is, an excessive amount of minority carriers is stored in the base of the bipolar transistor. As a result, the transistor cannot immediately respond to a subsequent transition in its operational state. As a result, such a conventional horizontal deflection output circuit having a bipolar transistor is not suitable for use in high-frequency horizontal scanning (above 30 KHz).
The following patents are considered to be representative of the prior art relative to the present invention, and are burdened by the disadvantage discussed above: U.S. Pat. No. 5,325,025 to Gawell et al., entitled Multiple Frequency Horizontal Scan Compensation System, U.S. Pat. No. 5,138,240 to Shimura, entitled Horizontal Deflection Driving Circuit, U.S. Pat. No. 5,089,756 to Hennig, entitled Deflection Driver In A Video Apparatus, U.S. Pat. No. 5,068,581 to Nishiura et al., entitled Horizontal Deflection Circuit For High-Frequency Scanning, U.S. Pat. No. 5,019,754 to Onozawa et al., entitled Horizontal Deflection Circuit, U.S. Pat. No. 4,897,581 to Oguino et al., entitled Horizontal Deflection Circuit, U.S. Pat. No. 4,719,394 to Watanuki, entitled Horizontal Output Circuit, U.S. Pat. No. 4,707,640 to Onozawa et al, entitled Horizontal Deflection Output Circuit, U.S. Pat. No. 4,472,662 to Freed, entitled Deflection Circuit, U.S. Pat. No. 4,442,384 to Maekawa et al., entitled Horizontal Deflection Circuit, U.S. Pat. No. 4,238,714 to Sumi, entitled Horizontal Deflection Output Circuit, U.S. Pat. No. 4,206,388 to Ishigaki et al., entitled Current Control Circuit For Horizontal Deflection Coil Of Television Receiver, U.S. Pat. No. 4,115,725 to Hashimoto, entitled Horizontal Deflection Circuit, U.S. Pat. No. 4,019,093 to Klein, entitled Horizontal Dynamic Damper Circuitry, U.S. Pat. No. 3,999,101 to Fischman et al, entitled Horizontal Deflection System, U.S. Pat. No. 3,980,927 to Haferl, entitled Deflection Circuit, U.S. Pat. No. 3,978,372 to Iwabuchi, entitled Vertical Deflection Output Circuit, U.S. Pat. No. 3,931,545 to Marino, entitled Horizontal Deflection Circuit, and U.S. Pat. No. 3,795,835 to Aldrich et al., entitled Horizontal Linearity Correction Circuit.